SQL & PL/SQL

I'm passing in codes like the following to the stored procedure (below):
",IRE,UK,FR,SCOT,WALES" (a string of words seperated by a ',')

Problem is I get the following error:
ORA-00936: missing expression ORA-06512: at "APPNAME.PKG_TOOL", line 132 ORA-06512: at line 1

I googled the two ORA's but am still stumped. I'd appreciate any help at all as I'm still not overly familiar with SQL.

PROCEDURE sp_check_code_Exist(p_CodeList IN varchar, p_cursorSMB IN OUT cursorSMB) IS
	thissql varchar(1000);

	BEGIN

		thissql := thissql || 'select * from codes_data c where ';
		thissql := thissql || 'c.code in ('|| p_CodeList ||') ';

		open p_cursor FOR thissql;

		begin
		 	 Execute immediate thissql;
		end;

	END sp_check_code_Exist;